Master Ophthalmology
for DHA

What the DHA Tests in Ophthalmology

The DHA exam tests Ophthalmology as a core clinical subject focusing on acute presentations (red eye, sudden vision loss), chronic conditions (glaucoma, diabetic retinopathy), and trauma. Candidates must demonstrate decision-making for referral, first-line pharmacotherapy, and interpretation of basic ophthalmoscopy findings. Emphasis is on emergency triage (e.g., differentiating conjunctivitis from acute angle closure glaucoma), management of diabetic eye disease according to international guidelines, and recognition of sight-threatening conditions like retinal detachment, central retinal artery occlusion, and giant cell arteritis. Knowledge of topical drug classes (antibiotics, beta-blockers, carbonic anhydrase inhibitors) and their contraindications is expected. The exam avoids rare syndromes and focuses on conditions encountered in primary care and emergency settings in the UAE.

High-Yield Concepts

• Acute Red Eye: Differential Diagnosis: Key distinction: conjunctivitis (diffuse injection, discharge, no pain/photophobia) vs. keratitis (pain, photophobia, corneal staining) vs. acute angle closure glaucoma (severe pain, fixed mid-dilated pupil, raised IOP >40 mmHg, corneal oedema) vs. anterior uveitis (circumcorneal injection, small pupil, cells/flare in anterior chamber). First-line: conjunctivitis – topical chloramphenicol or fusidic acid; keratitis – urgent ophthalmology referral; acute glaucoma – IV acetazolamide 500 mg + topical pilocarpine 2% + beta-blocker; uveitis – topical steroid (dexamethasone) and cycloplegic (cyclopentolate).
• Glaucoma Management Targets: Primary open-angle glaucoma: target IOP reduction of 25-30% from baseline, usually starting with a prostaglandin analogue (latanoprost 0.005% nocte). If IOP remains >21 mmHg, add timolol 0.5% bd. Angle closure: definitive treatment is laser peripheral iridotomy; acute attack requires immediate IOP lowering. Normal-tension glaucoma: target IOP <15 mmHg. Diabetic patients: annual screening for glaucoma is not routine unless IOP >21 mmHg or optic disc changes.
• Diabetic Retinopathy: Screening & Referral: Annual fundus photography for all diabetics. Referral criteria: moderate non-proliferative DR (more than 20 haemorrhages in 4 quadrants, venous beading, IRMA) – refer to ophthalmologist; proliferative DR (neovascularisation, vitreous haemorrhage) – urgent referral; diabetic macular oedema (thickening within 500 microns of fovea) – refer for possible intravitreal anti-VEGF (ranibizumab or aflibercept). HbA1c target <7% (53 mmol/mol) to slow progression. Panretinal photocoagulation indicated for high-risk PDR.
• Sudden Painless Vision Loss: Central retinal artery occlusion: afferent pupillary defect, cherry-red spot, retinal whitening; immediate referral for ocular massage, acetazolamide, and anterior chamber paracentesis if within 6 hours. Central retinal vein occlusion: CRVO with ischaemia (relative afferent defect, >10 disc areas of capillary non-perfusion) – urgent laser to prevent neovascular glaucoma. Optic neuritis: painful eye movement, reduced colour vision, central scotoma; treat with IV methylprednisolone 1 g daily for 3 days if MS suspected. Giant cell arteritis: suspect in >50 years with headache, jaw claudication, ESR >50 mm/hr; immediate high-dose prednisolone 60-80 mg daily to prevent blindness.
• Cataract: Indications for Surgery: Surgery indicated when visual acuity ≤6/12 (Snellen) or when cataract causes significant functional impairment (glare, difficulty driving, falls). Pre-op biometry: axial length and keratometry for IOL power calculation. Contraindications: active infection (blepharitis, conjunctivitis), uncontrolled glaucoma, macular degeneration with poor potential vision. Post-op endophthalmitis prophylaxis: topical chloramphenicol qds for 1 week; if suspected (pain, hypopyon, vision loss) – urgent vitreous tap and intravitreal vancomycin 1 mg + ceftazidime 2.25 mg.
• Topical Ocular Drugs: Key Classes: Antibiotics: chloramphenicol (first-line for bacterial conjunctivitis), fusidic acid (staph coverage), gentamicin (pseudomonas, but corneal toxicity). Beta-blockers: timolol 0.5% (first-line for glaucoma, contraindicated in asthma/bradycardia). Prostaglandin analogues: latanoprost (increases uveoscleral outflow, side effect: iris hyperpigmentation). Carbonic anhydrase inhibitors: dorzolamide 2% (topical, for glaucoma). Steroids: dexamethasone 0.1% (potent, for uveitis, keratitis – never use in dendritic ulcer). Cycloplegics: cyclopentolate 1% (diagnostic mydriasis, treatment of uveitis).
• Ocular Trauma: Initial Management: Chemical burns: immediate irrigation with 2 L normal saline, check pH, refer urgently. Open globe injury: shield (no pressure), IV antibiotics (ceftazidime + vancomycin), tetanus prophylaxis, nil per os, urgent repair. Orbital blowout fracture: assess for diplopia, enophthalmos, infraorbital nerve anaesthesia; CT orbits; surgery if muscle entrapment or >2 mm enophthalmos. Hyphema: strict bed rest, head elevated 30°, topical cycloplegic (atropine 1%) and steroid; monitor IOP; if IOP >30 mmHg >5 days, consider anterior chamber washout.
• Amblyopia and Strabismus in Children: Amblyopia: best corrected visual acuity difference of ≥2 lines between eyes, or VA ≤6/12 in one eye; treat with patching of good eye (2-6 hours/day) or atropine 1% penalisation. Strabismus: cover test for manifest/tropia; refer if constant esotropia >10 prism dioptres or any new-onset strabismus in child >6 months. Critical period: treat before age 7 for best outcome. DHA expects knowledge of red reflex test for leukocoria (retinoblastoma) at birth and 6-week check.

Common Traps in Ophthalmology Questions

• Confusing conjunctivitis with keratitis – keratitis always requires fluorescein staining and urgent referral; never prescribe topical steroids without ruling out dendritic ulcer.
• Using timolol in a patient with asthma or COPD – beta-blockers can precipitate bronchospasm; always check respiratory history.
• Assuming all red eyes with pain are conjunctivitis – acute angle closure glaucoma presents with severe pain, nausea, and fixed pupil; check IOP.
• Delaying steroids in giant cell arteritis while awaiting biopsy – start prednisolone immediately if clinical suspicion; biopsy can be done within 1 week.
• Failing to refer diabetic retinopathy with macular oedema – any thickening near fovea requires anti-VEGF treatment, not observation.
• Treating hyphema with aspirin or anticoagulants – these worsen bleeding; stop anticoagulants if safe and consult haematology.

How to Revise Ophthalmology for the DHA

For the DHA Ophthalmology section, prioritise acute presentations: red eye (differentiate four causes), sudden vision loss (arterial vs. venous occlusion, optic neuritis, GCA), and trauma (chemical burns, open globe). Memorise first-line drugs with doses and contraindications – especially topical beta-blockers and steroids. Practice interpreting Snellen acuity, Ishihara plates, and direct ophthalmoscopy findings (disc cupping, haemorrhages, cotton wool spots). Questions are often scenario-based: e.g., 'A 65-year-old diabetic with blurry vision and macular oedema – next step?' Answer: refer for intravitreal anti-VEGF. Know referral thresholds: VA ≤6/12 for cataract, IOP >21 mmHg for glaucoma, any neovascularisation. Focus on UK/European guidelines (NICE, RCOphth) for diabetic screening and glaucoma management. Avoid rare syndromes; the exam tests common, treatable conditions.

Practise it: MedLumen has 50 Ophthalmology questions for the DHA, each with a full explanation and references.